U.S. patent application number 10/309329 was filed with the patent office on 2003-07-10 for information communication apparatus, information communication method, and information communication process program.
This patent application is currently assigned to PIONEER CORPORATION. Invention is credited to Kondo, Hiromi, Usuba, Hidemi.
Application Number | 20030131122 10/309329 |
Document ID | / |
Family ID | 19179571 |
Filed Date | 2003-07-10 |
United States Patent
Application |
20030131122 |
Kind Code |
A1 |
Kondo, Hiromi ; et
al. |
July 10, 2003 |
Information communication apparatus, information communication
method, and information communication process program
Abstract
An information communication apparatus is provided with: a data
preparation section which generates communication data having a
predetermined data form for transfer to a serial bus based on data
such as audio or video data; a communication section including a
communication layer; and a control section which controls the data
preparation section and communication section, and determines a
data transmission speed based on issuance of a transaction and
reception of an acknowledge packet.
Inventors: |
Kondo, Hiromi;
(Tokorozawa-shi, JP) ; Usuba, Hidemi;
(Tokorozawa-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 Pennsylvania Avenue, NW
Washington
DC
20037-3213
US
|
Assignee: |
PIONEER CORPORATION
|
Family ID: |
19179571 |
Appl. No.: |
10/309329 |
Filed: |
December 4, 2002 |
Current U.S.
Class: |
709/233 ;
710/106 |
Current CPC
Class: |
H04L 5/1446 20130101;
H04L 1/1685 20130101; H04L 2001/125 20130101; Y02D 50/10 20180101;
Y02D 30/50 20200801; H04L 1/1671 20130101 |
Class at
Publication: |
709/233 ;
710/106 |
International
Class: |
G06F 015/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2001 |
JP |
P2001-370331 |
Claims
What is claimed is:
1. An information communication apparatus for setting any one of a
plurality of transmission speeds to a data transmission speed as a
transmission speed at a time when data communication with another
information communication apparatus is performed, and for
performing the data communication, the apparatus comprising: a
transmission device which uses any one of the plurality of
transmission speeds to transmit confirmation information for
confirming whether or not the data communication with said another
information communication apparatus can be performed; a detection
device which detects reception information indicating that said
another information communication apparatus has normally received
the confirmation information, the reception information being
transmitted from said another information communication apparatus;
and a determination device which determines the data transmission
speed based on presence or absence of detection of the reception
information in the detection device.
2. The information communication apparatus according to claim 1,
wherein the determination device comprises: a setting device which
sets the transmission speed at a time when the transmission device
has transmitted the confirmation information to the data
transmission speed, when the detection device detects the reception
information; and a retransmission device which retransmits the
confirmation information at the transmission speed different from
the transmission speed at the time when the transmission device has
transmitted the confirmation information, when the detection device
does not detect the reception information.
3. The information communication apparatus according to claim 2,
wherein the retransmission device repeatedly changes the
transmission speed and repeatedly retransmits the confirmation
information until the detection device detects the reception
information.
4. The information communication apparatus according to claim 3,
wherein the retransmission device successively changes the
transmission speed to the transmission speed lower than the
transmission speed of the confirmation information and retransmits
the confirmation information, when the detection device does not
detect the reception information.
5. The information communication apparatus according to claim 1,
wherein the determination device comprises: a retransmission device
which retransmits the confirmation information at the transmission
speed different from the transmission speed at the time when the
transmission device has transmitted the confirmation information,
when the detection device detects the reception information; and a
setting device which sets the transmission speed lower than the
transmission speed at the time when the confirmation information
has been transmitted to the data transmission speed, when the
detection device does not detect the reception information.
6. The information communication apparatus according to claim 5,
wherein the retransmission device repeatedly changes the
transmission speed and repeatedly retransmits the confirmation
information until the detection device does not detect the
reception information.
7. The information communication apparatus according to claim 6,
wherein the retransmission device successively changes the
transmission speed to the transmission speed higher than the
transmission speed of the confirmation information and retransmits
the confirmation information, when the detection device detects
said reception information.
8. The information communication apparatus according to claim 5,
wherein the transmission device starts the transmission of the
confirmation information at a low transmission speed next to a
lowest transmission speed.
9. The information communication apparatus according to claim 1,
further comprising: a selection device which selects a change order
of the transmission speed of the confirmation information as to
whether the retransmission device successively changes the
transmission speed to the low transmission speed from the high
transmission speed or to the high transmission speed from the low
transmission speed to retransmit the confirmation information; and
an acquisition device which acquires information of a maximum
transmission speed in said another information communication
apparatus beforehand, wherein the selection device selects the
change order of the transmission speed based on the acquired
maximum transmission speed.
10. The information communication apparatus according to claim 1,
wherein the confirmation information is communication request
information by which said another information communication
apparatus is requested to perform the data communication.
11. The information communication apparatus according to claim 1,
wherein the communication with said another information
communication apparatus is performed by a serial transmission
system.
12. The information communication apparatus according to claim 1,
wherein the communication with said another information
communication apparatus, the transmission device, and the reception
device conform to an Institute of Electrical and Electronic
Engineers (IEEE) 1394 standard.
13. An information communication method of setting any one of a
plurality of transmission speeds to a data transmission speed as a
transmission speed at a time when data communication with another
information communication apparatus is performed, and performing
the data communication, the method comprising: a transmission
process of using any one of the plurality of transmission speeds to
transmit confirmation information for confirming whether or not the
data communication with said another information communication
apparatus can be performed; a detection process of detecting
reception information indicating that said another information
communication apparatus has normally received the confirmation
information, the reception information being transmitted from said
another information communication apparatus; and a determination
process of determining the data transmission speed based on
presence or absence of detection of the reception information in
the detection process.
14. The information communication method according to claim 13,
wherein the determination process comprises: a setting process of
setting the transmission speed at a time when the confirmation
information has been transmitted by the transmission process to the
data transmission speed, when the reception information is detected
by the detection process; and a retransmission process of
retransmitting the confirmation information at the transmission
speed different from the transmission speed at the time when the
confirmation information has been transmitted by the transmission
process, when the reception information is not detected by said
detection process.
15. The information communication method according to claim 14,
wherein the retransmission process comprises the processes of:
repeatedly changing the transmission speed and repeatedly
retransmitting the confirmation information until the reception
information is detected by the detection process.
16. The information communication method according to claim 15,
wherein the retransmission process comprises the processes of:
successively changing the transmission speed to the transmission
speed lower than the transmission speed of the confirmation
information and retransmitting the confirmation information, when
the reception information is not detected by the detection
process.
17. The information communication method according to claim 13
wherein the determination process comprises: a retransmission
process of retransmitting the confirmation information at the
transmission speed different from the transmission speed at the
time when the confirmation information has been transmitted by the
transmission process, when the reception information is detected by
the detection process; and a setting process of setting the
transmission speed lower than the transmission speed at the time
when the confirmation information has been transmitted to the data
transmission speed, when said reception information is not detected
by the detection process.
18. The information communication method according to claim 17,
wherein the retransmission process comprises the processes of:
repeatedly changing the transmission speed and repeatedly
retransmitting the confirmation information until the reception
information is not detected by the detection process.
19. The information communication method according to claim 18,
wherein the retransmission process comprises the processes of:
successively changing the transmission speed to the transmission
speed higher than the transmission speed of the confirmation
information and retransmitting the confirmation information, when
the reception information is detected by the detection process.
20. The information communication method according to claim 17,
wherein the transmission process comprises the processes of:
starting the transmission of the confirmation information at a low
transmission speed next to a lowest transmission speed.
21. The information communication method according to claim 13,
further comprising: a selection process of selecting a change order
of the transmission speed of the confirmation information as to
whether the transmission speed is successively changed to the low
transmission speed from the high transmission speed or to the high
transmission speed from the low transmission speed to retransmit
the confirmation information by the retransmission process; and an
acquisition process of acquiring information of a maximum
transmission speed in the another information communication
apparatus beforehand, wherein the selection process comprises the
steps of: selecting the change order of the transmission speed
based on the acquired maximum transmission speed.
22. The information communication method according to claim 13,
wherein the confirmation information is communication request
information by which said another information communication
apparatus is requested to perform the data communication.
23. The information communication method according to claim 13,
wherein the communication with said another information
communication apparatus is performed by a serial transmission
system.
24. The information communication method according to claim 13,
wherein the communication with said another information
communication apparatus, the transmission process, and a reception
process conform to an Institute of Electrical and Electronic
Engineers (IEEE) 1394 standard.
25. An information communication process program embodied on an
information recording medium for setting any one of a plurality of
transmission speeds to a data transmission speed as a transmission
speed at a time when data communication with another information
communication apparatus is performed, and for performing the data
communication by a computer, the program causing the computer to
function as: a transmission device for using any one of the
plurality of transmission speeds to transmit confirmation
information for confirming whether or not the data communication
with said another information communication apparatus can be
performed; a detection device for detecting reception information
indicating that said another information communication apparatus
has normally received the confirmation information, the reception
information being transmitted from said another information
communication apparatus; and a determination device for determining
the data transmission speed based on presence or absence of
detection of said reception information.
26. The information communication process program embodied on an
information recording medium according to claim 25, wherein the
program causes the computer to function as: a setting device for
setting the transmission speed at a time when the confirmation
information has been transmitted to the data transmission speed,
when the confirmation information is transmitted and the reception
information is detected; and a retransmission device for
retransmitting the confirmation information at the transmission
speed different from the transmission speed at the time when the
confirmation information has been transmitted, when the detection
device does not detect the reception information.
27. The information communication process program embodied on an
information recording medium according to claim 26, wherein the
program causes the computer to function as a retransmission device
for repeatedly changing the transmission speed and repeatedly
retransmitting the confirmation information until the reception
information is detected.
28. The information communication process program embodied on an
information recording medium according to claim 27, wherein the
program causes the computer to function as a retransmission device
for successively changing the transmission speed to the
transmission speed lower than the transmission speed of the
confirmation information and retransmitting the confirmation
information, when the reception information is not detected.
29. The information communication process program embodied on an
information recording medium according to claim 25, wherein the
program causes the computer to function as: a retransmission device
for retransmitting the confirmation information at the transmission
speed different from the transmission speed at the time when the
confirmation information has been transmitted, when the
confirmation information is transmitted and the reception
information is detected; and a setting device for setting the
transmission speed lower than the transmission speed at the time
when the confirmation information has been transmitted to the data
transmission speed, when the reception information is not
detected.
30. The information communication process program embodied on an
information recording medium according to claim 29, wherein the
program causes the computer to function as a retransmission device
for repeatedly changing the transmission speed and repeatedly
retransmitting the confirmation information until the reception
information is not detected.
31. The information communication process program embodied on an
information recording medium according to claim 30, wherein the
program causes the computer to function as a retransmission device
for successively changing the transmission speed to the
transmission speed higher than the transmission speed of the
confirmation information and retransmitting the confirmation
information, when the reception information is detected.
32. The information communication process program embodied on an
information recording medium according to claim 29, wherein the
program causes the computer to function as a transmission device
for starting the transmission of the confirmation information at a
low transmission speed next to a lowest transmission speed.
33. The information communication process program embodied on an
information recording medium according to claim 25, wherein the
program causes the computer to function as: a selection device for
selecting a change order of the transmission speed of the
confirmation information as to whether the transmission speed is
successively changed to the low transmission speed from the high
transmission speed or to the high transmission speed from the low
transmission speed to retransmit the confirmation information; and
an acquisition device for acquiring information of a maximum
transmission speed in said another information communication
apparatus beforehand, wherein a selection device selects the change
order of the transmission speed based on the acquired maximum
transmission speed.
34. The information communication process program embodied on an
information recording medium according to claim 25, wherein the
confirmation information is communication request information by
which said another information communication apparatus is requested
to perform said data communication.
35. The information communication process program embodied on an
information recording medium according to claim 25, wherein the
communication with said another information communication apparatus
is performed by a serial transmission system.
36. The information communication process program embodied on an
information recording medium according to claim 25, wherein the
communication with said another information communication
apparatus, the transmission device, and a reception device conform
to an Institute of Electrical and Electronic Engineers (IEEE) 1394
standard.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a technical field
concerning a transmission speed of data communication, particularly
to a technical field of a transmission speed setting in a serial
transmission system in conformity with IEEE 1394 standard.
[0003] 2. Description of the Related Art
[0004] In recent years, with rapid spread of digital contents and
digitization of package media, there has been an increasing
importance of a technique of IEEE 1394 standard (formal name is
"IEEE Std. 1394 to 1995 IEEE Standard for a High Performance Serial
Bus") which has an effect useful for transfer of digital data.
[0005] In general, the IEEE 1394 standard is appropriate for
transferring AV digital data such as audio and video data.
[0006] In the IEEE 1394 standard, a plurality of information
processing apparatuses (hereinafter referred to simply as nodes)
are connected to one another via a serial bus, and information
transmission for a plurality of channels is standardized to be
executed among these nodes in a time division manner (a system
connected via one serial bus is standardized such that 63 different
channels at maximum can be used to transmit information in the
standard). Furthermore, high-speed serial transmission is
standardized to be performed at any transmission speed of 100 bits
per second (Mbps) (hereinafter referred to as S100), 200 bps
(hereinafter referred to as S200), and 400 bps (hereinafter
referred to as S400).
[0007] Moreover, in the IEEE 1394 standard, when another node is
newly connected to a group of nodes already connected to one
another via the serial bus (i.e., a bus connection time) or when
the node is disconnected from the node group (i.e., a bus release
time), initialization of the serial bus, so-called bus reset, is
standardized to be executed. With the bus reset, a predetermined
processing is executed as described later, and a new connection
mode of the serial bus (hereinafter referred to as topology) is
constructed, so that a degree of freedom in the connection mode is
enhanced, and user friendliness is enhanced.
[0008] Furthermore, the IEEE 1394 standard includes two types of
data transmission systems: an asynchronous transfer mode; and an
isochronous transfer mode.
[0009] The asynchronous transfer mode refers to communication
guaranteed to securely transmit a packet to a destination node. In
the asynchronous transfer mode, a transmission node transmits
header information and actual data to a designated destination
node, and the node having received the data returns acknowledgment
information indicating the reception (reception information), for
example, a so-called acknowledge packet to confirm the
reception.
[0010] Moreover, the isochronous transfer mode refers to a
communication performed in synchronization with a cycle start
packet transmitted at a given interval (125 .mu.sec) by only one
cycle master node, disposed on the bus, for managing a clock common
to the bus. In the isochronous transfer mode, instead of
transmitting the packet to a specific node, any one of a plurality
of channels is used to transmit the packet (isochronous packet
described later) to the whole bus, and a node having received the
data does not return the acknowledge packet, different from the
asynchronous transfer mode.
[0011] In the IEEE 1394 standard, a method of determining a maximum
transmission speed of a packet in the asynchronous transfer mode
(hereinafter referred to as the asynchronous packet) or a packet in
the isochronous transfer mode (hereinafter referred to as the
isochronous packet) between a node which is to transfer the data
(hereinafter referred to as the self node) and a node which
receives the data (hereinafter referred to the opposite node) has
heretofore comprised: (1) recognizing the connection mode of all
nodes in a transmission channel (hereinafter referred to as all the
channel nodes), and acquiring a transmission speed (PHY SPEED) for
physical layers (physical layer chips) of all the channel nodes;
(2) acquiring a transmission speed (LINK SPEED) for link layers
(link layer chips) of the opposite node; and (3) analyzing the
topology.
[0012] (1) Acquisition of Transmission Speed (PHY SPEED) in
Physical Layers of All Channel Nodes
[0013] The acquiring of the transmission speeds (PHY SPEED) in the
physical layers of all the channel nodes comprises: acquiring self
identification information (self-ID packet) transmitted from the
respective nodes after the bus reset to acquire the transmission
speed.
[0014] The self identification information (self-ID packet) in each
node is transmitted as follows.
[0015] When the bus reset occurs, first a process of identifying
all connection modes of the connected nodes (tree identify) is
performed. In this process, orientation to a root node is
determined with respect to all connected ports, so that one node is
finally selected as the root node.
[0016] Subsequently, the self identification process of each node
(self identify) is performed. In this process, each node acquires
only identification information (physical layer ID) of the bus
necessary for the identification, and transmits the self
identification information (self-ID packet) necessary for bus
management, such as the physical layer ID and information of the
transmission speed of the self node.
[0017] Each node acquires the self identification information
(self-ID packet) of another node transmitted in this manner, and
acquires the transmission speed information of each node in all the
channel nodes.
[0018] It is to be noted that FIG. 9 is a diagram showing data
structure of self identification information (self-ID packet) 1
transmitted by each node. In the diagram, (phy ID) 2 is
identification information of the physical layer in the self node,
(SP) 3 is information of the transmission speed in the physical
layer, p0 to p2 are information of a connection situation of the
self node described later, and the other areas are data areas
including the other information.
[0019] Moreover, another node reads the (SP) 3 to acquire the
transmission speed. For example, with "00.sub.2", S100 is
indicated, with "01.sub.2", S200 is indicated, and with "10.sub.2",
S400 is indicated. Furthermore, the self identification information
(self-ID packet) includes the other data.
[0020] (2) Acquisition of Transmission Speed (LINK SPEED) in Link
Layer of Opposite Node
[0021] The acquiring of the transmission speed (LINK SPEED) in the
link layer of the opposite node comprises: transmitting various
types of communication request information indicating a
communication request for data communication in the asynchronous
transfer mode (in the 1394 standard, the communication request
information is referred to as a transaction and the transmission of
the communication request information is referred to as issuance of
the transaction); and acquiring the transmission speed of the link
layer written in a configuration ROM in which information peculiar
to the apparatus is stored.
[0022] Concretely, the self node issues the transaction, reads data
for four bytes (one quadlet) from a bus information block 5 in the
configuration ROM shown in FIG. 10 in the opposite node, acquires
(link spd) 6 with the transmission speed written therein in the bus
information block, and acquires the transmission speed of the
opposite node.
[0023] It is to be noted that similarly as the physical layer
(SP)3, for example, "00.sub.2", "01.sub.2", "10.sub.2" are
described in the (link spd) 6 and indicate S100, S200, and S400,
respectively. Moreover, this bus information block 5 includes: a
bit (cyc clk acc) 7 indicating a clock accuracy of a synchronous
communication time; (node vendor ID) 8, (chip ID) 9 indicating IDs
unique to the apparatus; and other data areas 4.
[0024] (3) Topology Analysis
[0025] The topology analysis comprises: determining the maximum
transmission speed at which the data can be transmitted based on
the transmission speed of all the channel nodes acquired as
described above and the transmission speed at which the reception
is possible in the connected opposite node. That is, in the
topology analysis, it is judged whether or not another node is
connected between the self and opposite nodes, and the transmission
speed is determined in the connection situation.
[0026] It is to be noted that a method of judging the connection of
another node between the self and opposite nodes comprises:
analyzing the connection situations in the node, such as the
connection situation of a "node connected on a route side", "node
connected on a side opposite to the route side", and "unconnected
node" by p0, p1, p2 of the self identification information (self-ID
packet) shown in FIG. 9 to recognize the channel to the opposite
node; and acquiring node information in the middle of the
channel.
[0027] One example in which the transmission speed is determined
between the nodes in the conventional IEEE 1394 standard will next
be described.
[0028] For example, as shown in FIG. 11, an apparatus B exists
between an apparatus A which transfers data and an apparatus C to
which the data is transferred. The transmission speed (PHY SPEED)
in the physical layer of the apparatus A and the transmission speed
(LINK SPEED) in the link layer are S400, the transmission speed
(PHY SPEED) in the physical layer in the apparatus B is S200, and
the transmission speed (LINK SPEED) in the link layer is S100.
Moreover, the transmission speed (PHY SPEED) in the physical layer
of the apparatus C and the transmission speed (LINK SPEED) in the
link layer are S400. In this case, the maximum transmission speed
at which the transmission between the nodes via the link layers of
the apparatuses A and B is possible is S100, and the maximum
transmission speed at which the transmission between the nodes via
the link layers of the apparatuses A and C is possible is S200.
[0029] However, the above-described determination method of the
transmission speed in the conventional IEEE 1394 standard needs to
comprise: (1) acquiring the transmission speeds (PHY SPEED) in the
physical layers of all the channel nodes; (2) acquiring the
transmission speeds (LINK SPEED) in the link layers of the opposite
node (including the other nodes in the transfer channel); and (3)
analyzing the topology as described above. If these steps are not
performed, it is impossible to determine the maximum transmission
speed at which the transmission is possible. There is a problem
that the performing of these steps requires much time.
[0030] Moreover, when there are a large number of nodes, the
topology analysis becomes complicated. The number of processes
required until the transmission speed is determined increases This
causes a problem that a process efficiency is deteriorated.
[0031] Furthermore, the IEEE 1394 standard concretely includes IEEE
1394 to 1995 standards and IEEE 1394a to 2000 standards. The IEEE
1394 to 1995 standards do not include the above-described (link
spd) which is disposed in the bus information block and in which
the transmission speed is described. Therefore, the transmission
speed in the link layer is judged to be unclear, and this also
causes a problem that it is impossible to set an appropriate
transmission speed.
SUMMARY OF THE INVENTION
[0032] The present invention has been developed in consideration of
the above-described problems, and an object thereof is to provide
an information communication apparatus in which a transmission
speed between nodes in an IEEE 1394 standard can appropriately be
set and a process efficiency in a determination process of the
transmission speed can be enhanced.
[0033] The above object of the present invention can be achieved by
an information communication apparatus of the present invention for
setting any one of a plurality of transmission speeds to a data
transmission speed as a transmission speed at a time when data
communication with another information communication apparatus is
performed, and for performing the data communication. The apparatus
is provided with: a transmission device which uses any one of the
plurality of transmission speeds to transmit confirmation
information for confirming whether or not the data communication
with said another information communication apparatus can be
performed; a detection device which detects reception information
indicating that said another information communication apparatus
has normally received the confirmation information, the reception
information being transmitted from said another information
communication apparatus; and a determination device which
determines the data transmission speed based on presence or absence
of detection of the reception information in the detection
device.
[0034] According to the present invention, any one of a plurality
of transmission speeds is used to transmit confirmation
information, reception information indicating that another
information communication apparatus has normally received the
confirmation information is detected, and a data transmission speed
is determined based on presence or absence of detection of the
reception information.
[0035] Therefore, the data transmission speed of a transmission
time of the data can be determined by the transmission speed at
which the confirmation information is normally received in a
plurality of transmission speeds. Moreover, it is possible to judge
whether or not the information is normally received only by the
presence or absence of detection of the reception information.
Therefore, an optimum transmission speed can easily be set.
[0036] In one aspect of the present invention, the determination
device is provided with: a setting device which sets the
transmission speed at a time when the transmission device has
transmitted the confirmation information to the data transmission
speed, when the detection device detects the reception information;
and a retransmission device which retransmits the confirmation
information at the transmission speed different from the
transmission speed at the time when the transmission device has
transmitted the confirmation information, when the detection device
does not detect the reception information.
[0037] According to this aspect, any one of a plurality of
transmission speeds is used to transmit confirmation information.
When the reception information is detected, the transmission speed
of the transmission time of the confirmation information is set to
the data transmission speed. When the reception information is not
detected, the transmission speed is changed to the transmission
speed different from the transmission speed for use in the
transmission of the confirmation information and the confirmation
information is retransmitted.
[0038] Therefore, the reception information indicating that the
information is normally received by another information
communication apparatus is detected, and thereby the transmission
speed at which data communication is possible can be detected. The
transmission speed at which the data communication is possible can
be set to the data transmission speed. Therefore, the optimum data
transmission speed can easily and accurately be set.
[0039] In another aspect of the present invention, the
retransmission device repeatedly changes the transmission speed and
repeatedly retransmits the confirmation information until the
detection device detects the reception information.
[0040] According to this aspect, the transmission speed is changed
and the confirmation information is repeatedly retransmitted until
the reception information is detected.
[0041] Therefore, the transmission speed at which the data
communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0042] In further aspect of the present invention, the
retransmission device successively changes the transmission speed
to the transmission speed lower than the transmission speed of the
confirmation information and retransmits the confirmation
information, when the detection device does not detect the
reception information.
[0043] According to this aspect, when the reception information is
not detected, the transmission speed is successively changed to a
transmission speed lower than the transmission speed of the
confirmation information and the confirmation information is
retransmitted.
[0044] Therefore, when another information communication apparatus
keeps pace with the high transmission speed, process burdens in
setting the data transmission speed can be alleviated. Moreover,
the transmission speed at which the data communication is possible
can easily be detected, and the appropriate data transmission speed
can accurately be set.
[0045] In further aspect of the present invention, the
determination device comprises: a retransmission device which
retransmits the confirmation information at the transmission speed
different from the transmission speed at the time when the
transmission device has transmitted the confirmation information,
when the detection device detects the reception information; and a
setting device which sets the transmission speed lower than the
transmission speed at the time when the confirmation information
has been transmitted to the data transmission speed, when the
detection device does not detect the reception information.
[0046] According to this aspect, any one of a plurality of
transmission speeds is used to transmit the confirmation
information. When the reception information is detected, the
transmission speed is changed to the transmission speed different
from the transmission speed of the transmission time of the
confirmation information and the confirmation information is
retransmitted. When the reception information is not detected, the
data transmission speed is set to the transmission speed lower than
the transmission speed for use in the transmission of the
confirmation information.
[0047] Therefore, the reception information indicating that the
information is normally received by another information
communication apparatus is detected, and thereby the transmission
speed at which the data communication is possible can be detected.
Moreover, the transmission speed at which the data communication is
possible can be set to the data transmission speed, and it is
therefore possible to easily set the optimum data transmission
speed.
[0048] In further aspect of the present invention, the
retransmission device repeatedly changes the transmission speed and
repeatedly retransmits the confirmation information until the
detection device does not detect the reception information.
[0049] According to this aspect, the transmission speed is changed
and the confirmation information is repeatedly retransmitted until
the reception information is not detected any more.
[0050] Therefore, the transmission speed at which the data
communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0051] In further aspect of the present invention, the
retransmission device successively changes the transmission speed
to the transmission speed higher than the transmission speed of the
confirmation information and retransmits the confirmation
information, when the detection device detects said reception
information.
[0052] According to this aspect, when the reception information is
detected, the transmission speed is successively changed to the
transmission speed higher than the transmission speed of the
confirmation information and the confirmation information is
retransmitted.
[0053] Therefore, when another information communication apparatus
keeps pace with the low transmission speed, the process burdens in
setting the data transmission speed can be alleviated. Moreover,
the transmission speed at which the data communication is possible
can easily be detected, and the appropriate data transmission speed
can accurately be set.
[0054] In further aspect of the present invention, the transmission
device starts the transmission of the confirmation information at a
low transmission speed next to a lowest transmission speed.
[0055] According to this aspect, the transmission of the
confirmation information is started at a low transmission speed
next to a lowest transmission speed. When another information
communication apparatus keeps pace with the low transmission speed,
the process burden in setting the data transmission speed can be
alleviated. Moreover, the transmission speed at which the data
communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0056] In further aspect of the present invention, the information
communication apparatus further comprises: a selection device which
selects a change order of the transmission speed of the
confirmation information as to whether the retransmission device
successively changes the transmission speed to the low transmission
speed from the high transmission speed or to the high transmission
speed from the low transmission speed to retransmit the
confirmation information; and an acquisition device which acquires
information of a maximum transmission speed in said another
information communication apparatus beforehand, wherein the
selection device selects the change order of the transmission speed
based on the acquired maximum transmission speed.
[0057] According to this aspect, a change order of the transmission
speed of the confirmation information is selected based on the
maximum transmission speed of another information communication
apparatus acquired beforehand.
[0058] Therefore, even with the other information communication
apparatus which keeps pace with the low transmission speed, or even
with the other information communication apparatus which keeps pace
with the high transmission speed, the transmission speed at which
the data communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0059] In further aspect of the present invention, the confirmation
information is communication request information by which said
another information communication apparatus is requested to perform
the data communication.
[0060] According to this aspect, the appropriate data transmission
speed can easily and accurately be set before the data
communication is performed.
[0061] In further aspect of the present invention, the
communication with said another information communication apparatus
is performed by a serial transmission system.
[0062] According to this aspect, the data transmission speed can
easily be set with respect to communication which is performed by a
serial transmission system.
[0063] In further aspect of the present invention, the
communication with said another information communication
apparatus, the transmission device, and the reception device
conform to an Institute of Electrical and Electronic Engineers
(IEEE) 1394 standard.
[0064] According to this aspect, the appropriate data transmission
speed can easily and accurately be set with respect to the
communication which conforms to an IEEE 1394 standard.
[0065] The above object of the present invention can be achieved by
an information communication method of the present invention for
setting any one of a plurality of transmission speeds to a data
transmission speed as a transmission speed at a time when data
communication with another information communication apparatus is
performed, and performing the data communication. The method is
provided with: a transmission process of using any one of the
plurality of transmission speeds to transmit confirmation
information for confirming whether or not the data communication
with said another information communication apparatus can be
performed; a detection process of detecting reception information
indicating that said another information communication apparatus
has normally received the confirmation information, the reception
information being transmitted from said another information
communication apparatus; and a determination process of determining
the data transmission speed based on presence or absence of
detection of the reception information in the detection
process.
[0066] According to the present invention, any one of a plurality
of transmission speeds is used to transmit confirmation
information, the reception information indicating that another
information communication apparatus has normally received the
confirmation information is detected, and the data transmission
speed is determined based on the presence or absence of detection
of the reception information.
[0067] Therefore, the transmission speed of the transmission time
of the data can be determined by the transmission speed at which
the confirmation information is normally received in a plurality of
transmission speeds. Moreover, it is possible to judge whether or
not the information is normally received only by the
presence/absence of the detection of the reception information.
Therefore, the optimum transmission speed can easily be set.
[0068] In one aspect of the present invention, the determination
process comprises: a setting process of setting the transmission
speed at a time when the confirmation information has been
transmitted by the transmission process to the data transmission
speed, when the reception information is detected by the detection
process; and a retransmission process of retransmitting the
confirmation information at the transmission speed different from
the transmission speed at the time when the confirmation
information has been transmitted by the transmission process, when
the reception information is not detected by said detection
process.
[0069] According to this aspect, any one of a plurality of
transmission speeds is used to transmit the confirmation
information. When the reception information is detected, the
transmission speed of the transmission time of the confirmation
information is set to the data transmission speed. When the
reception information is not detected, the transmission speed is
changed to the transmission speed different from the transmission
speed for use in the transmission of the confirmation information
and the confirmation information is retransmitted.
[0070] Therefore, the reception information indicating that the
information is normally received by another information
communication apparatus is detected, and thereby the transmission
speed at which the data communication is possible can be detected.
The transmission speed at which the data communication is possible
can be set to the data transmission speed. Therefore, the optimum
data transmission speed can easily and accurately be set.
[0071] In another aspect of the present invention, the
retransmission process comprises the processes of: repeatedly
changing the transmission speed and repeatedly retransmitting the
confirmation information until the reception information is
detected by the detection process.
[0072] According to this aspect, the transmission speed is changed
and the confirmation information is repeatedly retransmitted until
the reception information is detected.
[0073] Therefore, the transmission speed at which the data
communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0074] In further aspect of the present invention, the
retransmission process comprises the processes of: successively
changing the transmission speed to the transmission speed lower
than the transmission speed of the confirmation information and
retransmitting the confirmation information, when the reception
information is not detected by the detection process.
[0075] According to this aspect, when the reception information is
not detected, the transmission speed is successively changed to the
transmission speed lower than the transmission speed of the
confirmation information and the confirmation information is
retransmitted.
[0076] Therefore, when another information communication apparatus
keeps pace with the high transmission speed, the process burdens in
setting the data transmission speed can be alleviated. Moreover,
the transmission speed at which the data communication is possible
can easily be detected, and the appropriate data transmission speed
can accurately be set.
[0077] In further aspect of the present invention, the
determination process comprises: a retransmission process of
retransmitting the confirmation information at the transmission
speed different from the transmission speed at the time when the
confirmation information has been transmitted by the transmission
process, when the reception information is detected by the
detection process; and a setting process of setting the
transmission speed lower than the transmission speed at the time
when the confirmation information has been transmitted to the data
transmission speed, when said reception information is not detected
by the detection process.
[0078] According to this aspect, any one of a plurality of
transmission speeds is used to transmit the confirmation
information. When the reception information is detected, the
transmission speed is changed to the transmission speed different
from the transmission speed of the transmission time of the
confirmation information and the confirmation information is
retransmitted. When the reception information is not detected, the
data transmission speed is set to the transmission speed lower than
the transmission speed for use in the transmission of the
confirmation information.
[0079] Therefore, the reception information indicating that the
information is normally received by another information
communication apparatus is detected, and thereby the transmission
speed at which the data communication is possible can be detected.
The transmission speed at which the data communication is possible
can be set to the data transmission speed. Therefore, the optimum
data transmission speed can easily be set.
[0080] In further aspect of the present invention, the
retransmission process comprises the processes of: repeatedly
changing the transmission speed and repeatedly retransmitting the
confirmation information until the reception information is not
detected by the detection process.
[0081] According to this aspect, the transmission speed is changed
and the confirmation information is repeatedly retransmitted until
the reception information is not detected any more.
[0082] Therefore, the transmission speed at which the data
communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0083] In further aspect of the present invention, the
retransmission process comprises the processes of: successively
changing the transmission speed to the transmission speed higher
than the transmission speed of the confirmation information and
retransmitting the confirmation information, when the reception
information is detected by the detection process.
[0084] According to this aspect, when the reception information is
detected, the transmission speed is successively changed to the
transmission speed higher than the transmission speed of the
confirmation information and the confirmation information is
retransmitted.
[0085] Therefore, when another information communication apparatus
keeps pace with the low transmission speed, the process burdens in
setting the data transmission speed can be alleviated. Moreover,
the transmission speed at which the data communication is possible
can easily be detected, and the appropriate data transmission speed
can accurately be set.
[0086] In further aspect of the present invention, the transmission
process comprises the processes of: starting the transmission of
the confirmation information at a low transmission speed next to a
lowest transmission speed.
[0087] According to this aspect, the transmission of the
confirmation information is started at the low transmission speed
next to the lowest transmission speed. When another information
communication apparatus keeps pace with the low transmission speed,
the process burdens in setting the data transmission speed can be
alleviated. Moreover, the transmission speed at which the data
communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0088] In further aspect of the present invention, the information
communication method further comprises: a selection process of
selecting a change order of the transmission speed of the
confirmation information as to whether the transmission speed is
successively changed to the low transmission speed from the high
transmission speed or to the high transmission speed from the low
transmission speed to retransmit the confirmation information by
the retransmission process; and an acquisition process of acquiring
information of a maximum transmission speed in the another
information communication apparatus beforehand, wherein the
selection process comprises the steps of: selecting the change
order of the transmission speed based on the acquired maximum
transmission speed.
[0089] According to this aspect, the change order of the
transmission speed of the confirmation information is selected
based on the maximum transmission speed of another information
communication apparatus acquired beforehand.
[0090] Therefore, even with the other information communication
apparatus which keeps pace with the low transmission speed, or even
with the other information communication apparatus which keeps pace
with the high transmission speed, the transmission speed at which
the data communication is possible can easily be detected, and the
appropriate data transmission speed can accurately be set.
[0091] In further aspect of the present invention, the confirmation
information is communication request information by which said
another information communication apparatus is requested to perform
the data communication According to this aspect, the appropriate
data transmission speed can easily and accurately be set before the
data communication is performed.
[0092] In further aspect of the present invention, the
communication with said another information communication apparatus
is performed by a serial transmission system.
[0093] According to this aspect, the data transmission speed can
easily be set with respect to the communication which is performed
by the serial transmission system.
[0094] In further aspect of the present invention, the
communication with said another information communication
apparatus, the transmission process, and a reception process
conform to an Institute of Electrical and Electronic Engineers
(IEEE) 1394 standard.
[0095] According to this aspect, the appropriate data transmission
speed can easily and accurately be set with respect to the
communication which conforms to the IEEE 1394 standard.
BRIEF DESCRIPTION OF THE DRAWINGS
[0096] FIG. 1 is a diagram showing a constitution of a
communication layer of an IEEE 1394 standard;
[0097] FIG. 2 is a diagram showing a constitution of a transaction
packet of the IEEE 1394 standard;
[0098] FIG. 3A is an explanatory view of an operation of one
asynchronous arbitration in the IEEE 1394 standard, and FIG. 3B is
a diagram showing a constitution of an acknowledge packet in one
asynchronous arbitration;
[0099] FIG. 4 is a block diagram showing a constitution of an
information communication apparatus according to the present
invention;
[0100] FIG. 5 is a flowchart showing an operation of a
determination process of a transmission speed in a first
embodiment;
[0101] FIG. 6 is a flowchart showing one example of the operation
of the determination process of the transmission speed in the first
embodiment;
[0102] FIG. 7 is a flowchart showing the operation of the
determination process of the transmission speed in a second
embodiment;
[0103] FIG. 8 is a flowchart showing one example of the operation
of the determination process of the transmission speed in the
second embodiment;
[0104] FIG. 9 is a diagram showing a packet constitution of self
identification information in the IEEE 1394 standard;
[0105] FIG. 10 is a diagram showing a constitution of a bus
information block in the IEEE 1394 standard; and
[0106] FIG. 11 is a diagram showing one example of a conventional
determination operation of the transmission speed between nodes in
the IEEE 1394 standard.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0107] Preferred embodiments of the present invention will next be
described with reference to the drawings.
[0108] It is to be noted that the embodiments described hereinafter
refer to the present invention applied to an information
communication apparatus including a serial bus conforming to an
IEEE 1394 standard.
[0109] I. IEEE 1394 Standard
[0110] First, an outline of the IEEE 1394 standard in conformity
with which recording information is transmitted according to the
embodiments will be described before concrete description of the
embodiments.
[0111] As described above, in the IEEE 1394 standard, nodes as a
plurality of information processing apparatuses are connected to
one another via a serial bus, and information transmission for a
plurality of channels is standardized to be executed among these
nodes in a time division manner.
[0112] In the IEEE 1394 standard (hereinafter referred to simply as
a serial bus standard), when another node is newly connected to a
group of nodes already connected to one another via the serial bus
(i.e., a bus connection time) or when the node is disconnected from
the node group (i.e., a bus release time), initialization of the
serial bus, so-called bus reset, is standardized to be executed.
Moreover, with the bus reset, the following processing is executed,
and a new topology of the serial bus is constructed.
[0113] (1) The node having detected a change of a connection state
transmits a bus reset signal indicating occurrence of bus reset to
another node connected via the serial bus, and the node having
received the signal transmits the bus reset signal to still another
connected node, so that the signal is transmitted to all the
nodes.
[0114] (2) Subsequently, after the bus reset, the individually
connected nodes are identified so as to be treated as the nodes
connected in a tree shape, and orientations of all the connected
nodes with respect to a root node are determined, so that one node
is selected as the root node (tree identification process).
[0115] (3) Subsequently, the selected root node determines only one
piece of identification information (physical ID) in the bus
necessary for the identification of each node, and transmits self
identification information (self-ID packet) necessary for bus
management (self identification process).
[0116] (4) Finally, during a self identification procedure period,
each node monitors the self-ID packets from the other nodes, and
sets an isochronous resource manager (IRM) node which supplies a
register for allocating communication channels and bands.
[0117] A new topology after the bus reset is constituted through
the above-described four processes.
[0118] Subsequently, when the information is actually transmitted
after the constitution of the topology, a transmission node as a
node to start the transmission of the information refers the
present communication state of another node to the IRM node. When
the channel and band to be used by the self node are usable, the
transmission node acquires a right to transmit the information
(more concretely, the transmission node secures the channel and
band for use by the transmission node) and starts the information
transmission.
[0119] A communication layer will next be described which is
connected to another information communication apparatus and which
performs a communication control with the other information
communication apparatus and transmits/receives the data.
[0120] It is to be noted that FIG. 1 is an explanatory view of the
communication layer defined by the IEEE 1394 standard.
[0121] As shown in FIG. 1, an IEEE 1394 standard communication
layer 10 includes a serial bus management section 14 which manages
a serial bus, and a three-layered structure including a transaction
layer 11, link layer 12, and physical layer 13. The transaction
layer 11, link layer 12, and physical layer 13 communicate with one
another, and these layers individually communicate with the serial
bus management section 14. Moreover, the transaction layer 11 and
link layer 12 communicate with an application layer 15 as an upper
function block.
[0122] Concretely, the transaction layer 11 performs read, write,
and lock processes described later (hereinafter referred to as
read, write, and lock transactions, respectively) to read and write
the data in asynchronous transmission so that an asynchronous data
transmission service for the application layer 15 to perform the
data communication with the other apparatuses is provided.
[0123] It is to be noted that for the application layer 15 to
transmit isochronous data, a data preparation section 16 prepares
the data to be transmitted in a predetermined form and the data is
transmitted to each apparatus.
[0124] The link layer 12 includes a packet transmission section 22
and packet reception section 23 which perform an address processing
and data error check, and a cycle control section 24 which controls
a cycle described later.
[0125] It is to be noted that a request for an isochronous
transmission service described later is made to the link layer 12
from the application layer 15 not via the transaction layer 11.
That is, the link layer 12 directly transmits/receives the
isochronous data with respect to the data preparation section 16
which prepares various types of data in the predetermined form for
the data transmission.
[0126] The physical layer 13 includes: a mechanical interface 17
which performs a mechanical interface process, such as a connector
cable required for physical connection to the other information
communication apparatuses; an encode/decode section 18 which
converts a logic symbol for use in the link layer 12 and a signal
for use in the physical layer 13; an electrical interface 19 which
performs an electrical interface process to determine an electrical
level of a communication signal; an arbitration section 20 to
perform an arbitration process so that only one node starts the
data transmission; a resynchronization section 21 which
resynchronizes a communication clock; and a bus initialization
process section 22 which executes reconfiguration of the IEEE 1394
serial bus with the bus reset.
[0127] Asynchronous and isochronous transfer modes will next be
described briefly.
[0128] In the IEEE 1394 standard, the data is divided into packets,
and transmitted on a basis of cycle having a length of 125 .mu.sec
in time division. This cycle is produced by a cycle start signal
supplied from a node which has a cycle master function.
[0129] In the isochronous transfer mode, the data is transmitted by
the isochronous transmission performed by an isochronous packet
which secures a band necessary for the transmission from the top of
all the cycles. In the isochronous transmission, the transmission
of the data within a given time is guaranteed. However, there is no
structure for protecting the data to be transmitted by the
isochronous transmission, when a transmission error is generated.
Therefore, the data having the error is lost.
[0130] Moreover, in the asynchronous transfer mode, in a time of
each cycle unused by the isochronous transmission, as a result of
arbitration, the node having secured the IEEE 1394 serial bus sends
an asynchronous packet to perform the asynchronous transmission.
For this asynchronous transmission, acknowledge and retry are used
as described later to securely guarantee the transmission, but a
transmission timing is not constant.
[0131] It is to be noted that in the isochronous transmission, a
time length of an isochronous transmission area in one isochronous
cycle is standardized to be 100 .mu.sec at maximum. Therefore, the
information allocated to each channel in one isochronous
transmission area needs to have a total transmission time of 100
.mu.sec or less.
[0132] A transaction in the asynchronous transfer mode will next be
described.
[0133] As described above, in the asynchronous transfer mode, the
acknowledge and retry are used to perform the data transmission. As
shown in FIG. 2, the transmission node transmits header information
and actual data to a destination node, and the reception node
returns an acknowledge packet to report the reception of the
packet.
[0134] It is to be noted that as shown in FIG. 2 a data packet 30
to be transmitted in the asynchronous transfer mode is constituted
of a header portion 31 and actual data portion 32. Moreover,
(destination ID) 33 indicates identification information of a
packet transmission destination, (tl) 34 indicates information for
recognizing agreement of a pair of transactions of request and
response packets, (tcode) 35 indicates type information of the
transaction, and (source ID) 36 indicates the identification
information of a transmitter of the packet.
[0135] In this asynchronous transfer mode, a process of
transmitting one piece of packet data (hereinafter referred to as
an asynchronous sub action) is executed as follows (see FIG.
3A).
[0136] First, the node which is to transmit the packet starts
arbitration in a data transmission waiting state. Subsequently, the
transmission node which has overcome the arbitration, that is,
which is ready to perform a transfer operation adds a reception
waiting signal 43 instructing a reception state and data end
information 44 to the data packet 30 including the header
information and actual data, and transmits the data packet.
Finally, the node having received the data transmits an acknowledge
packet 45 indicating a reception situation to the transmission node
immediately after the reception.
[0137] It is to be noted that as shown in FIG. 3B the acknowledge
packet 45 includes not only the reception waiting signal 43 and
data end information 44 but also an acknowledgment code 46 and
acknowledgment parity 47.
[0138] These transaction functions include three types of
functions: read; write; and lock. The read transaction is a
function of reading a designated length of data from a target
address of the opposite node, and the write transaction is a
function of writing the designated length of data into the target
address of the opposite node. Moreover, the lock transaction is a
function of performing a given process by the transmission and
reception nodes based on a predetermined instruction. Examples of
this process include a compare swap transaction, mask swap
transaction, and fetch address lock transaction.
[0139] II. Embodiments
[0140] An information communication apparatus according to
embodiments will next be described with reference to FIGS. 4 to 6.
In the embodiments, a transmission speed at which the data is
transmitted by the above-described IEEE 1394 standard is
determined.
[0141] It is to be noted that in the present embodiments, a process
(hereinafter referred to simply as a determination process) of
using a read transaction operation to determine the transmission
speed will be described.
[0142] [First Embodiment]
[0143] A constitution of the information communication apparatus in
a first embodiment will first be described with reference to FIGS.
4, 5.
[0144] It is to be noted that FIG. 4 is a block diagram showing the
constitution of the first embodiment, and FIG. 5 is a flowchart
showing an operation of the transmission speed determination
process in the first embodiment.
[0145] An information communication apparatus 200 shown in FIG. 4
includes: the application layer 15 which uses a protocol higher in
rank than the 1394 standard and the 1394 standard to perform the
communication; the data preparation section 16 which prepares
communication data having a predetermined data form for transfer to
the serial bus based on audio or video data; a communication
section 100 including a communication layer having the
three-layered structure of the transaction layer 11, link layer 12,
and physical layer 13; and a control section 101 which controls the
data preparation section 16 and communication section 100.
[0146] It is to be noted that the control section 101 constitutes
transmission, detection, determination, setting and retransmission
devicess according to the present invention.
[0147] The application layer 15 uses the protocol higher in rank
than the 1394 standard and the 1394 standard to perform the
communication, additionally operates the other apparatuses in
response to a user's request, and informs a user of the apparatuses
connected to the bus.
[0148] To the data preparation section 16, AV data such as audio
and video data outputted from audio and video reproduction sections
(not shown) are inputted. The data preparation section 16 holds
real time properties of the inputted AV data, converts the data to
communication data having a predetermined form, and outputs the
converted communication data to the communication section 100.
[0149] As described above, the communication section 100 includes
three layers of the transaction layer 11, link layer 12, and
physical layer 13, and the serial bus management section 14. The
transaction layer 11, link layer 12, and physical layer 13 have the
above-described constitutions.
[0150] The control section 101 is mainly constituted of a CPU and
memory, transmits/receives necessary control information via the
bus, and generally controls the respective constituting members.
Moreover, the information necessary for the general control is
temporarily stored in the memory via the bus and used for the
general control.
[0151] A determination process of the transmission speed of the
first embodiment and a transmission speed for communicating with
the other apparatuses will next be described with reference to FIG.
5.
[0152] It is to be noted that the determination process of the
transmission speed is performed by the control section 101.
[0153] First, the control section 101 issues the read transaction
at a maximum transmission speed of the self node (step S11). It is
to be noted that the transmission speed in issuing the read
transaction is referred to as a trial speed (TRY SPEED).
[0154] Concretely, the arbitration is performed. When the node
overcomes the arbitration, the control section writes type
information of the read transaction in the (source ID) 36 in the
data packet 30, and transmits the data packet 30 to the opposite
node via the transaction layer 11 at the maximum transmission
speed.
[0155] Subsequently, the control section 101 judges whether or not
the acknowledge packet 45 received by the transaction layer 11 is
returned (step S12). The control section judges that the packet has
been returned, and the control section 101 then sets the trial
speed at which the read transaction is issued in the previous step
(step S11, or step S16 described later) to the transmission speed
at which the communication is performed (step S13), and ends the
operation. That is, when the trial speed is the maximum
transmission speed, the transmission speed is maximized.
[0156] On the other hand, the control section 101 judges that the
acknowledge packet 45 is not returned, and then judges whether or
not the trial speed in the issuance of the read transaction is S200
(step S14).
[0157] In this case, when the trial speed is judged to be S200, the
transmission speed for performing the communication is set to S100
(step S15) and the control section 101 ends the operation. When the
trial speed is judged to be other than S200, the trial speed for
issuing the read transaction is changed to a one step lower speed,
and the data packet 30 in the read transaction is again transmitted
to the opposite node (step S16).
[0158] Thereafter, that is, after the data packet 30 in the read
transaction is transmitted to the opposite node, the process shifts
to the step S12, and the process of and after the step S12 is
repeated.
[0159] The transmission speed for transmitting the communication
data can be determined by the transaction function in the
asynchronous transfer mode in this manner.
[0160] Moreover, for example, when the transmission speed is set to
S400, S200, and S100 in order from the maximum transmission speed,
the determination process of the transmission speed according to
the first embodiment is as follows.
[0161] It is to be noted that FIG. 6 shows a flowchart of the
determination process of the transmission speed of the first
embodiment applied to the transmission speed set to S400, S200, and
S100.
[0162] First, the control section 101 issues the read transaction
by the maximum transmission speed (trial speed) S400 of the self
node (step S21). Subsequently, the control section 101 judges
whether or not the acknowledge packet 45 received by the
transaction layer 11 is returned (step S22). When the control
section 101 judges the packet to be returned, the control section
sets the transmission speed to S400 (step S23) and ends the
operation.
[0163] On the other hand, the control section 101 judges that the
acknowledge packet 45 is not returned, then changes the transfer
speed for issuing the read transaction to a one step lower speed
(S200), again transmits the data packet 30 in the read transaction
to the opposite node (step S24), and again judges whether or not
the acknowledge packet 45 received by the transaction layer 11 is
returned (step S25). When the control section judges the packet to
be returned, the section sets the trial speed S200 to the
transmission speed and ends the operation (step S26).
[0164] On the other hand, the control section 101 judges that the
acknowledge packet 45 is not returned, and sets the minimum
transmission speed S100 to the transmission speed (step S27).
[0165] As described above, according to the first embodiment, any
one of a plurality of transmission speeds is used to transmit the
read transaction, and the acknowledge packet indicating that
another information communication apparatus has received a request
for the transaction is detected. In this case, the transmission
speed for transmitting the read transaction is set to the
transmission speed of the data communication. When this acknowledge
packet is not detected, the transmission speed is changed to the
transmission speed lower than the transmission speed for use in the
transmission of the transaction, and confirmation information can
be retransmitted. Therefore, an optimum transmission speed can
easily and accurately be set in the IEEE 1394 standard.
[0166] Moreover, the transmission speed is successively changed to
the low speed and the read transaction is repeatedly issued until
the acknowledge packet is detected. Therefore, it is possible to
easily detect a transmission speed at which the communication is
possible in the IEEE 1394 standard.
[0167] It is to be noted that in the first embodiment the
transmission speed is determined by the read transaction function
in the asynchronous transfer mode, but transmission speed may also
be determined, when another transaction is issued.
[0168] Moreover, in the first embodiment, the transmission speed
set to S100, S200, and S400 has been described. When the
information communication apparatus having the transmission speed
equal to or higher than the above-described transmission speed is
recognized by the topology analysis, the process is started at the
maximum speed recognized by the topology analysis.
[0169] Furthermore, in the first embodiment, the control section
101 issues the read transaction and performs the determination
process of the transmission speed. However, a computer and
recording medium may be disposed in the control section 101, the
program for performing the determination process of the
transmission speed may be stored in the recording medium directly
or via networks such as Internet, and the stored program may be
read by the computer to execute the determination process of the
transmission speed.
[0170] [Second Embodiment]
[0171] The constitution of the information communication apparatus
in a second embodiment will next be described with reference to
FIGS. 7, 8.
[0172] It is to be noted that in the first embodiment the
transmission speed is successively changed to the low speed from
the maximum transmission speed of the self node and the
transmission speed of the communication data is determined. The
second embodiment is different in that the transmission speed is
successively changed to a high transmission speed from the minimum
transmission speed of the self node and the transmission speed of
the communication data is determined. The second embodiment is
similar to the first embodiment in the other constitutions of the
information communication apparatus. Therefore, the same member is
denoted with the same reference numeral and the description thereof
is omitted.
[0173] Moreover, FIG. 7 is a flowchart showing the operation of the
transmission speed determination process of the second
embodiment.
[0174] Furthermore, similarly as the first embodiment, the
determination process of the transmission speed is controlled by
the control section 101, and the optimum transmission speeds of the
self and opposite nodes are determined.
[0175] First, the control section 101 issues the read transaction
using the low transmission speed next to the lowest transmission
speed of the self node as the trial speed (step S31).
[0176] Concretely, similarly as the first embodiment, the
arbitration is performed. When the node overcomes the arbitration,
the control section writes the type information of the read
transaction in (source ID) 36 in the data packet 30, and transmits
the data packet 30 to the opposite node at the low transmission
speed next to the lowest transmission speed via the transaction
layer 11.
[0177] It is to be noted that the lowest transmission speed
(usually S100) is recognized in all the nodes. Therefore, the read
transaction is issued using the low transmission speed next to the
lowest transmission speed as the trial speed. Additionally, the
transaction may also be issued at the lowest transmission
speed.
[0178] Subsequently, the control section 101 judges whether or not
the acknowledge packet 45 received by the transaction layer 11 is
returned (step S32). When the control section 101 judges the packet
not to be returned, the section sets the transmission speed lower
by one step than the trial speed used in issuing the read
transaction in the previous step (step S31, or step S36 described
later) to the transmission speed for performing the communication
(step S33), and ends the operation.
[0179] On the other hand, the control section 101 judges that the
acknowledge packet 45 is returned, and judges whether or not the
trial speed used in issuing the read transaction is the maximum
transmission speed (step S34).
[0180] In this case, when the trial speed used in issuing the read
transaction by the previous step (step S31, or step S36 described
later) is judged to be the maximum transmission speed in the step
S32, the transmission speed for performing the communication is set
to the maximum transmission speed of the self node (step S35) and
the control section 101 ends the operation. When the trial speed
used in issuing the read transaction is judged to be other than the
maximum transmission speed, the trial speed for issuing the read
transaction is changed to a one step higher speed, and the data
packet 30 in the read transaction is transmitted to the opposite
node (step S36).
[0181] Thereafter, that is, after the data packet 30 in the read
transaction is again transmitted to the opposite node, the process
shifts to step S32, and the process of and after the step S32 is
repeated.
[0182] As described above, the transmission speed for transmitting
the communication data can be determined by the transaction
function in the asynchronous transfer mode.
[0183] Moreover, for example, when the speed is set to S400, S200,
and S100 in order from the maximum transmission speed, the
determination process of the transmission speed of the second
embodiment is as follows.
[0184] It is to be noted that FIG. 8 is a flowchart of the
determination process of the transmission speed of the second
embodiment applied to the transmission speed set to S400, S200, and
S100.
[0185] First, the control section 101 sets the trial speed of the
self node to S200 and issues the read transaction at the trial
speed (step S41).
[0186] Subsequently, the control section 101 judges whether or not
the acknowledge-packet 45 received by the transaction layer 11 is
returned (step S42). When the control section 101 judges the packet
not to be returned, the control section sets the transmission speed
to S100 (step S43) and ends the operation.
[0187] On the other hand, the control section 101 judges that the
acknowledge packet 45 has been returned, then changes the trial
speed for issuing the read transaction to a one step higher speed
(S400), and again transmits the data packet 30 in the read
transaction to the opposite node (step S44).
[0188] Subsequently, the control section 101 again judges whether
or not the acknowledge packet 45 received by the transaction layer
11 is returned (step S45). When the control section 101 judges the
packet to be returned, the section sets the maximum transmission
speed S400 to the transmission speed and ends the operation (step
S46).
[0189] On the other hand, the control section 101 judges that the
acknowledge packet 45 is not returned, sets the trial speed S200 to
the transmission speed (step S47), and ends the operation.
[0190] As described above, according to the second embodiment,
among a plurality of transmission speeds, first the low
transmission speed next to the lowest transmission speed is used to
transmit the read transaction. When the acknowledge packet
transmitted from another information communication apparatus is
detected, the transmission speed is successively changed to the
transmission speed higher than the transmission speed for use in
the transmission of the transaction and confirmation information is
retransmitted. The transmission of the confirmation information is
repeated until the acknowledge packet is not detected any more.
Moreover, the data communication can be performed at the one step
lower transmission speed, when the acknowledge packet cannot be
detected. Therefore, a communicable transmission speed can easily
be detected in the IEEE 1394 standard, and the optimum transmission
speed can easily be set in the IEEE 1394 standard.
[0191] It is to be noted that in the second embodiment the
transmission speed is determined by the read transaction function
in the asynchronous transfer mode, but the transmission speed may
also be determined when the other transactions are issued.
[0192] Moreover, in the second embodiment, different from the first
embodiment, in the determination process of the transmission speed
in the control section 101, the transmission speed for issuing the
transaction is changed in order from the low transmission speed.
However, the control section may acquire the maximum transmission
speed of all the nodes in all connections, and select the high or
low transmission speed at which the transaction is issued based on
the acquired maximum transmission speed.
[0193] That is, when the maximum transmission speed in all the
nodes is high, for example, when a large number of nodes use S400,
the transaction is issued at the high transmission speed. When the
transmission speed is low, for example, when a large number of
nodes indicate S100 or an unclear speed, the transaction is issued
at the low transmission speed.
[0194] In this case, the control section 101 judges whether the
transaction is issued at the high or low transmission speed based
on the maximum transmission speed of the connected apparatus,
before performing the determination process of the transmission
speed. It is judged that the transaction is to be issued at the
high transmission speed, and the determination process of the
transmission speed of the first embodiment is performed (see FIG.
5). Alternatively, it is judged that the transaction is to be
issued at the low transmission speed, and the determination process
of the transmission speed of the second embodiment is performed
(see FIG. 7).
[0195] According to the constitution, when there are many
information communication apparatuses having the high transmission
speed in the connected information communication apparatuses, or
when there are many information communication apparatuses having
the low transmission speed, the transmission speed can be
determined in a short time in the transmission speed determination
process.
[0196] Furthermore, in the second embodiment, the transmission
speeds of S100, S200, and S400 have been described. However, when
an information communication apparatus having a higher transmission
speed is recognized by the topology analysis, the process is
performed up to the maximum speed recognized by the topology
analysis.
[0197] Additionally, in the second embodiment, the control section
101 issues the read transaction and performs the determination
process of the transmission speed. However, the computer and
recording medium may be disposed in the control section 101, so
that the program for performing the determination process of the
transmission speed may be stored in the recording medium directly
or via the networks such as Internet, and the stored program may be
read by the computer to execute the determination process of the
transmission speed.
[0198] As described above, according to the present invention, any
one of a plurality of transmission speeds is used to transmit the
confirmation information, the reception information indicating that
another information communication apparatus has normally received
the confirmation information is detected, and the data transmission
speed is determined based on the presence/absence of the detection
of the reception information. Therefore, the data transmission
speed for transmitting the data can be determined by the
transmission speed at which the confirmation information is
normally received in a plurality of transmission speeds. Moreover,
it can be judged whether or not the information has normally been
received only by the presence/absence of the detection of the
reception information. Therefore, the optimum transmission speed
can easily be set.
[0199] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The present embodiments are therefore to be considered in
all respects as illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description and all changes which come within the meaning
and range of equivalency of the claims are therefore intended to be
embraced therein.
[0200] The entire disclosure of Japanese Patent Application No.
2001-370331 filed on Dec. 4, 2001 including the specification,
claims, drawings and summary is incorporated herein by reference in
its entirety.
* * * * *